PROMISE trial analysis shows little difference over 3 years

Action Points

Note that this secondary analysis of a trial examining different initial imagine modalities for coronary artery disease revealed minimal total cost differences at 2 years of follow-up, regardless of strategy.

Be aware that threshold values for what might constitute meaningful increases in cost have not been well established.

The method used to diagnose patients with suspected coronary artery disease has little ultimate impact on the overall costs of care, a PROMISE substudy found.

According to Daniel B. Mark, MD, MPH, of Duke Clinical Research Institute in Durham, N.C., and colleagues, there were indeed differences in the mean costs of various diagnostic procedures:

Exercise electrocardiography at $174

CT angiography at $404

Pharmacologic stress echocardiography at $501

Exercise stress echocardiography at $514

Exercise stress nuclear testing at $946

Pharmacologic stress nuclear testing at $1,132

However, mean costs at 90 days -- including that of revascularizations and catheterizations -- totaled $2,494 for a CT angiography route versus $2,240 for a functional testing strategy, for a mean difference of just $254, the authors reported online in Annals of Internal Medicine, similar to findings initially presented at the American College of Cardiology meeting.

The cost difference between testing methods was $353 the first year and $26 the second year. Of note, the gap widened back to $249 the third year out.

But, "the year 3 results were skewed by an outlier in the CT angiography group that involved a hospitalization costing more than $300,000 for orthopedic care unrelated to the PROMISE testing question," Mark and colleagues wrote. "When this observation was removed, the mean difference between the groups in year 3 was reduced to $91."

The narrowed cost difference could be tied to more revascularizations and catheterizations following CT angiography, they noted, such that "CT angiography and functional diagnostic testing strategies in patients with suspected coronary artery disease have similar costs through 3 years of follow-up," they concluded.

The PROMISE trial previously showed similar outcomes for patients who underwent exercise/stress testing and those who got CT angiography, so it seemed plausible that it would come down to economics to dictate the choice between the two strategies.

Not anymore, said Joe X. Xie, MD, and Leslee J. Shaw, PhD, both of Emory University School of Medicine in Atlanta.

"A noteworthy PROMISE finding is that regardless of the index procedure, near-term costs varied little. Thus, the concept of the cost of the index procedure being of primary importance for resource allocation purposes may be misguided," they wrote in an accompanying editorial.

The study included 9,649 patients from the U.S. who were enrolled in the PROMISE trial between 2010 and 2013.

The investigators acknowledged that "no criteria have been established for defining how small a numerical difference must be for costs to qualify as 'similar' (a notion akin to 'noninferior' in the comparison of clinical outcomes)." Accordingly, a 90-day cost difference of $254 may be negligible to some -- and quite substantial to others.

Cost data were abstracted from the Premier Research Database and individual hospital records, which Mark's group noted was another limitation to the study: "The initial diagnostic test costs used in our analysis were derived from data from outside the trial, which was necessitated by the lack of suitable cost weights from the trial patients."

"Also, we did not include the costs of outpatient medications, routine outpatient medical care, or patient and caregiver time because of budget constraints," the authors wrote.

Xie and Shaw also suggested that the cost of disease management entails more than just diagnosis and revascularization, writing that "therapeutic management of suspected coronary artery disease includes a focus on symptom control, lifestyle modification, and targeted anti-ischemic and risk factor-modifying treatments."

As such, they wrote, "PROMISE lacks details on the costs of medical therapy related to symptom relief during follow-up. Preventive therapies for cardiovascular disease impart a heavy economic burden on the large population of patients with suspected coronary artery disease."

The editorialists nonetheless conceded that the authors reported "relatively low costs of care, especially after noncardiovascular costs were subtracted. These findings suggest that current expansive prior-authorization programs to control use of index procedures may be ill-advised," they concluded. "Further evidence is needed for the value of no-testing options."

The study was supported by the National Heart, Lung, and Blood Institute.

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